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need help jetting 520 big bore
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Posted by: jbuck

i have a 190main and 65piolt and it is out 2 1/2 turns on the screw and it is still hard to start but runs ok

Posted by: chad502ex

quote:
Originally posted by jbuck
i have a 190main and 65piolt and it is out 2 1/2 turns on the screw and it is still hard to start but runs ok

I have a copy of a NMotion 520 dyno sheet putting out 55.5rwhp. That's awesome on a bored, not stroked, motor! I' ll post as soon as I get it scanned into an .jpg. Amazing,...

Anyway, without a port/flow or valve work, I would think your 190 is about right with your setup, but the 65 seems to big to me without head work. After the motor is running at idle, does it hold or bobble? Also, with the throttle about 10% held for 1 min. does it start to bobble? If it does it'll tell you that your too rich.

hope this helps.
chad502ex.com

Posted by: kssandduner

quote:
I have a copy of a NMotion 520 dyno sheet putting out 55.5rwhp

Right on!! Those are my boys!!

Joe

Posted by: chad502ex

quote:
Originally posted by kssandduner
Right on!! Those are my boys!!

Joe

yes, I'll post soon. Are you saying that you got 55.5hp on your machine too?

Posted by: jbuck

my head is ported and polished and it idles fine its just hard to start and if i stall out it will not just sart back up i have to sit for a min and try to start it if i hold the hot start in it helps a little bit

Posted by: chad502ex

quote:
Originally posted by jbuck
my head is ported and polished and it idles fine its just hard to start and if i stall out it will not just sart back up i have to sit for a min and try to start it if i hold the hot start in it helps a little bit

yep, pilot to big, try a 50 or 52 pilot.

chad550r

Posted by: kssandduner

I'm just curious if the guys from Nmotion told you to run the 65? They're usually pretty close on their jetting specs, cause they test everything on their dyno. I would try dropping down a couple sizes on your pilot, but NOT all the way down to a 50! I run a 60 pilot jet in my R, and all I have is their full exhaust system and an HRC kit. I'm still fine tuning mine, but it's really close. Personally, I would call and talk to John and the boys before you alter things too much.

Joe

Posted by: jbuck

I thinki talk to john from nmotion and he told to put a 225 main and a 65piolt on a stock carb and i thought it was way to big i now have a 50piolt and 175main and it starts good and now and is pulling hard

Posted by: chad502ex

quote:
Originally posted by jbuck
I thinki talk to john from nmotion and he told to put a 225 main and a 65piolt on a stock carb and i thought it was way to big i now have a 50piolt and 175main and it starts good and now and is pulling hard

hmmm, 175 seems little too small.

good luck!

Posted by: want250rhere

getting ready to jet my nmotion 520

yosh full system
pro design filter
eh racing outerwears lid
stock head
curtis sparks cam

stock carb

trying 200 on the main and 50 on the pilot...

Posted by: jbuck

i would try a 185 first im at 1500above sea level and is the safest jet i like to run mine lean for more power and i have a 175 well hope that help if not let me know and il try and help